Vehicle headlights with a light source

Abstract

Vehicle headlight (4) with a light source and with an adjustable lens, characterized in that the light source is designed as an array (5) with a plurality of micro light sources, and in that the adjustable lens comprises at least three lens groups (K 1, K 2, K 3), of which at least two are designed to be displaceable along the optical axis (6) in order to adjust the focal length and the focal plane in order to adapt the size of the image in the desired illumination plane and to simultaneously focus the image in the desired illumination plane.

Description

[0001] The invention relates to a vehicle headlight with a light source and an adjustable lens.

[0002] Vehicle headlights with a light source and an adjustable lens are fundamentally known from the prior art. In this context, reference can be made to DE 10 2006 053 019 A1, for example. The adjustable lens here comprises at least one movable lens, which cooperates with a reflector and a gas discharge lamp as the light source. This makes it possible to widen the light beam accordingly, i.e., by adjusting the focal length, ultimately vary the magnification of the projection in the illumination plane. In practice, this entails the disadvantage of blurriness, since a sharp image is only possible in a structurally predetermined illumination plane at the corresponding focal length. Such blurriness is a serious disadvantage, particularly when appropriate measures are to be taken to mask out parts of a high beam cone, for example to reduce glare for oncoming traffic.

[0003] However, the technical trend is increasingly moving in precisely this direction. The aim is for the vehicle's surroundings to be recorded using environmental sensors. The detected objects are then classified and, if necessary, illuminated by appropriately controlling the headlight light source or excluded from the illumination, for example oncoming vehicles, in order to avoid dazzling them. In this context, DE 10 2015 013 271 A1 describes a setup that can achieve this using an LED pixel light source. DE 10 2015 013 271 A1 then describes, among other things, that sharply imaging optics would be desirable in order to bring the desired light image from the light source into the illumination plane and thus "onto the road" as intended. The disadvantage, however, is that such optics only enable a truly sharp image at a specific distance.Depending on the traffic situation, however, the distances between the illumination planes vary, which can lead to problems. For this reason, the aforementioned document proposes a movement between the optics and the array of pixel light sources, which in this case is achieved primarily by tilting the array of pixel light sources.

[0004] In practice, this is relatively complex and relatively limited in terms of focusing at different distances. Furthermore, independent adjustment of the image size in the illumination plane is not possible, as the light source beam cannot be expanded, as the focal length remains essentially the same.

[0005] US 2014 / 0175978 A1, the closest prior art, shows a light image projected onto an LED array via an optical system. The stated purpose is to expand the beam, which is achieved by shifting the light image and LED array along the optical axis. The focal length of the optical system remains constant, meaning the two-lens optical system is not adjusted. The disadvantage is that this only changes the magnification, but does not adjust the sharpness of the image.

[0006] Spotlights with variable lenses are also known from the further state of the art, particularly in the field of stage lighting technology, for example, from WO 2011 / 020920 A1 or DE 20 2011 000 481 U1. DE 93 01 883 U1 also originates from stage technology. It shows a zoom lens for a stage spotlight. This contains only two lens assemblies: the illumination lens and the condenser lens. Colored edges of the light beam are suppressed with a diaphragm. Stage spotlights do not produce a sharp image of the light sources, but rather strive for a uniform light distribution across the entire spot.

[0007] Furthermore, US 2018 / 0 132 330 A1 shows a light image in an LED array. This can be imaged using a fixed—non-adjustable—lens. The array is always imaged to infinity, and the outgoing rays run parallel. KR 10 2017 0 112 640 A also shows something similar.

[0008] US 2018 / 0 313 510 A1 shows a beam expansion of a digital mirror device for headlights. The lens system required for this does not include any adjustment. The digital mirror device, as the light source, is always projected to infinity.

[0009] WO 2017 / 066 817 A1 contains a microlens array without focal length adjustment and without beam expansion.

[0010] DE 10 2011 079 570 A1 contains a light control that influences incident external (sun)light when the headlight is switched off.

[0011] DE 10 2012 224 345 A1 contains an adjustable optical element with which the cut-off point in the illumination plane is adjusted.

[0012] DE 10 2004 012 519 A1 shows a reflection headlight with a condenser consisting of two lenses that can be adjusted relative to each other. The light source consists of a two-filament bulb for the low beam and high beam. The beam expansion can be adjusted by adjusting the focal length of the condenser system.

[0013] DE 10 2013 110 272 A1 shows two fixed lens groups for beam expansion and parallelization for an LED array.

[0014] Furthermore, US 2014 / 0 029 287 A1 shows the use of a diffraction grating to prevent chromatic aberrations in microlens systems. The light source contains a light image with a light-dark boundary, which is located in the focal plane of the projection lens and projected at a distance in front of the vehicle.

[0015] The object of the present invention is to further improve a vehicle headlight, in particular a headlight for a vehicle, with a light source and an adjustable lens with regard to its intended use.

[0016] According to the invention, this object is achieved by a vehicle headlight having the features in claim 1, and in particular in the characterizing part of claim 1. Advantageous embodiments and further developments emerge from the dependent claims.

[0017] Firstly, unlike previous headlights known from the prior art, the vehicle headlight according to the invention uses an array with a plurality of micro-light sources as its light source. Such an array with a plurality of micro-light sources, for example, micro-LEDs or micro-mirrors, which specifically direct the light in the desired direction or deflect it from it, allows for a very fine resolution of the resulting light image. The definition of a plurality of micro-light sources according to the present description includes a structure comprising more than 10,000, in particular between 30,000 and 1.5 million, micro-light sources.

[0018] This vehicle headlight design with an array of such micro light sources is now additionally provided with an adjustable lens. This lens has the special feature compared to lenses known from the prior art in that it comprises at least three lens assemblies, at least two of which are designed to be movable along the optical axis in order to adjust the focal length and the focal plane. The lens of the vehicle headlight with the plurality of micro light sources is thus designed such that it can, on the one hand, adjust the focal length and thus the magnification, and, on the other hand, adjust the focal plane. Such a lens has not previously been used in vehicle headlights, especially in vehicle headlights with a plurality of micro light sources. Its functional principle essentially corresponds to that of a zoom lens, as is known from photography.The inventor has recognized that this, when used in reverse in the vehicle headlight, allows both the size of the image in the desired illumination plane to be adjusted accordingly and the image to be focused simultaneously in the desired illumination plane. Thus, all the disadvantages described in the aforementioned prior art are avoided in the vehicle headlight according to the invention.

[0019] A high-resolution image created by the multitude of micro-light sources can now be displayed at any desired distance from the vehicle, in the desired size, and with high sharpness at the desired illumination level. The image of the specified light-dark distribution, which is derived in a conventional manner, particularly from the data of the vehicle's environmental sensors and the calculations of an intelligent lighting control system, can thus be projected very precisely and accurately "on the road" at the desired illumination level.

[0020] According to an advantageous development of the idea, each of the lens assemblies has at least one optical lens, so that the size and sharpness of the image of the light-dark distribution on the road can be influenced over a correspondingly large magnification range. Furthermore, an aperture stop can be provided and / or one or more of the surfaces of one or more elements of the lens can be aspherical. The materials of the individual elements of the lens can also have different refractive indices, so that different materials or materials with different densities can be used, in particular to achieve a simple and compact design. In addition, optical optimizations such as diffractive structures on the surfaces, anti-reflective coatings, variable liquid lenses, or the like can of course also be applied.

[0021] A further very advantageous embodiment of the headlight according to the invention provides, in addition or as an alternative, that the positioning of individual or several elements of the optical system relative to one another and / or the positioning of the entire optical system relative to the light source is realized by DC motors, stepper motors and / or piezo actuators.

[0022] Further advantageous embodiments of the idea also emerge from the embodiment, which is described in more detail below with reference to the figures.

[0023] Showing: Fig. 1 a schematic diagram of a vehicle in a view from above with a projection of a light-dark distribution in different sizes in an illumination plane caused by the headlights of the vehicle; Fig. 2 shows an exemplary adjustable lens for use in the headlight according to the invention in a first extreme position; Fig. 3 shows an exemplary adjustable lens for use in the headlight according to the invention in a second extreme position; Fig. 4 a schematic representation of the light cones of the headlights of a vehicle in the Fig. 2 shown extreme position; Fig. 5 a schematic representation of the light cones of the headlights of a vehicle in the Fig. 3 shown extreme position; Fig. 6 an exemplary representation of a simulated high beam distribution in the Fig. 2 shown extreme position; and Fig. 7 an example representation of a simulated high beam distribution in the Fig. 3 shown extreme position.

[0024] In the presentation of the Fig. 1 shows a bird's-eye view of a vehicle 1. In front of the vehicle 1, with a light image 2 in an illumination plane designated 3, the possibility of emitting light with different focal lengths and thus a different beam spread from the vehicle's headlights 4 (not visible here) is shown. A solid line indicates a small magnification 2a, and a dashed line a correspondingly larger magnification 2b of the light image 2 in the illumination plane 3 is indicated three-dimensionally.

[0025] In order to achieve the desired size 2a, 2b of the light image 2 in the illumination plane 3 as well as a high sharpness of the light image in the illumination plane 3, the vehicle headlight 4 can be Fig. 2 schematically indicated type. The vehicle headlight 4 has as light source an array 5 of micro light sources, which are controlled via an intelligent light control system not shown here in such a way that they specify a light-dark distribution as light image 2 for projection onto the road and into the illumination plane 3. This light image 2 is now, as shown in the principle diagram of the Fig. 2, is emitted into the environment along an optical axis 6. It passes through three lens assemblies K 1, K 2 and K 3. The lens assembly K 1, which here comprises, for example, two lenses 7, 8 and an aperture stop 9, is not displaceable along the optical axis 6 in the embodiment shown here and is accordingly fixed. This results in a defined distance to the field 5 of the micro light sources. The lens assembly K 2 also consists of two lenses 10, 11 and is displaceable along the optical axis 6, as indicated by the arrow labeled 12. In the embodiment shown here, it is Fig. 2 is shown directly adjacent to lens group K3 with a lens 13, and thus in one of its extreme positions, namely the "minimum focal length" position. The light exit cone, designated 14, is correspondingly wide. Lens group K3 is also movable, as indicated by arrow 15.

[0026] Optionally, the aperture diaphragm can also be designed to be movable. An additional iris diaphragm can also be included in the headlight.

[0027] In the presentation of the Fig. 4 shows a plan view of the vehicle 1 showing what the schematically indicated light cones 14 look like in this "minimum focal length" position of the lens groups K 1, K 2, K 3 of the headlights 4. They very quickly become correspondingly wide and are particularly suitable for illuminating a large area of ​​an illumination plane 3 (not shown here). The ability to shift the lens groups K 2 and K 3 as a whole relative to the lens group K 1 and relative to one another, in addition to the desired width of the exit light cones 14, the sharpness in the illumination plane 3 can also be precisely adjusted, so that in the desired illumination plane 3 an image of the field 5 of the micro light sources is provided both in a variable size and in the desired, typically maximum possible, sharpness.

[0028] The Fig. 6 shows the light distribution in this situation of the “minimum focal length” position based on a corresponding simulation, whereby the light distribution is brightest in the middle and the values ​​decrease towards the edge, as shown by the different gray levels in the representation of the Fig. 6 can be seen.

[0029] The representation of the Fig. 3 now uses the same representation as in Fig. 2. The lens assembly K 2 with its two lenses 10, 11 is now in its other extreme position, namely the "maximum focal length" position. The exit cone 14 of the light is therefore correspondingly narrower and extends to a greater distance, enabling it to specifically illuminate and detect objects there. Fig. 5 shows again analogous to Fig. 4 shows the corresponding view of the vehicle 1 with the exit light cones 14 from above. It is particularly clear from a direct comparison of the figures that the schematically illustrated exit light cones 14 are correspondingly narrower here and thus provide a higher light intensity even at a greater distance. This is also evident from the representation of the Fig. 7. Analogous to the representation in Fig. Figure 6 again shows the simulation of the light distribution. Overall, the illuminated area in the exemplary illumination plane 3 is correspondingly smaller, but the light intensity is significantly higher, especially in the center.

[0030] Between these two described extreme positions of the maximum focal length in the Fig. 3, Fig. 5 and Fig. 7 and the minimum focal length in the Fig. 2, Fig. 4 and Fig.6, any intermediate values ​​can now be set. This allows the image of the field 5 of micro light sources to be displayed in the desired illumination plane 3 in the required size and with the required sharpness, so that a multitude of different lighting tasks can be performed with the vehicle headlight 4 according to the invention, in particular also adaptive lighting in the sense described above, in which objects detected by environmental sensors can be specifically illuminated or not illuminated, for example, to prevent glare from oncoming traffic or self-glare from the very bright illumination of a traffic sign or the like. Furthermore, objects in the environment can be specifically illuminated in order to be able to better detect and classify them using environmental sensors such as cameras or the like.

Claims

[1] Vehicle headlight (4) with a light source and with an adjustable lens, characterized by , that the light source is designed as a field (5) with a plurality of micro light sources, and that the adjustable lens comprises at least three lens groups (K 1, K 2, K 3), of which at least two are designed to be displaceable along the optical axis (6) in order to adjust the focal length and the focal plane in order to adjust the size of the image in the desired illumination plane and to focus the image in the desired illumination plane at the same time. [2] Vehicle headlight (4) according to claim 1, characterized by that the micro light sources have micro-LEDs or micro-mirror devices. [3] Vehicle headlights (4) according to claim 1 or 2, characterized by , that the field (5) has a number of more than 10,000, in particular 30,000 to 1.5 million, micro light sources. [4] Vehicle headlights (4) according to claim 1, 2 or 3, characterized by , that each of the lens assemblies (K 1, K 2, K 3) has at least one optical lens (7, 8, 10, 11, 13). [5] Vehicle headlight (4) according to any one of claims 1 to 4, characterized by , that the adjustable lens has at least one aperture stop (9). [6] Vehicle headlight (4) according to any one of claims 1 to 5, characterized by that the lens also contains an iris diaphragm. [7] Vehicle headlight (4) according to any one of claims 1 to 6, characterized by that one or more surfaces of one or more optical elements of the variable lens are aspherical, have diffractive structures and / or an antireflective coating. [8] Vehicle headlight (4) according to any one of claims 1 to 7, characterized by , that the materials of individual optical elements of the variable lens have different refractive indices. [9] Vehicle headlight (4) according to any one of claims 1 to 8, characterized by , that the positioning of the lens assemblies (K 1, K 2, K 3) which can be moved along the optical axis (6) is realized by DC motors, stepper motors and / or piezo actuators.

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